Here, we present the first complete genome sequence of the strain PAMC 20958T from the genus Halo-cynthiibacter.Halocynthiibacterarcticus PAMC 20958T, isolated from a marine sediment of the Arctic, is a gram-negative, aerobic, and rod-shaped bacterium. The complete genome contains 4,329,554 base pairs with 53.21% GC content and a 44,566 base pair plasmid with 48.72% GC content. This genome contained genes encoding alkaline phosphatase and lipase, and genes that confer resistance to arsenic, cadmium, tellurite, and acriflavin.